Flame-retardant polycarbonate resin composition

ABSTRACT

A flame retardant polycarbonate resin composition comprises 100 parts by weight of a polycarbonate resin (A), 0.01 to 3 parts by weight of a silicone compound (B) having a branched chain structure and organic functional groups, wherein said organic functional groups comprise (I) aromatic groups or (ii) aromatic groups and hydrocarbon groups (excluding aromatic groups), 0.5 to 20 parts by weight of a phosphazene compound (C), 0.01 to 2 parts by weight of an organometallic salt (D) and 0.01 to 2 parts by weight of a fiber-forming type fluorine-containing polymer (E). 5 to 25 parts byweight of titanium oxide (F) and 0.05 to 2 parts by weight of a poly(organo hydrogen sioxane) (G), per 100 parts by weight of a polycarbonate resin (A), may be further added. Since the flame retardant polycarbonate resin composition of the present invention does not contain a halogen type flame retarding agent comprising chlorine compounds, bromine compounds and the like, no as derived from a halogen type flame retarding agent are generated when burned. Furthermore, the composition has a degree of flame retardance. a light reflectivity, and an excellent impact resistance, a heat resistance, a light resistance and can be used for various internal and external uses associated with electrical, electronic and OA applications.

FIELD OF THE INVENTION

The present invention relates to a flame retardant polycarbonate resincomposition obtained upon formulating a specific silicone compound, aspecific phosphazene compound, a specific organometallic salt, afiber-forming, fluorine containing polymer used as a dripping inhibitorand also, when desired, a specific titanium oxide and a poly(organohydrogen siloxane). The flame retardant polycarbonate resin compositionof the present invention has an excellent flame retardance and also anexcellent mechanical strength, molding properties and good appearance.Therefore, the composition can be used in a wide ranging variety ofapplications, particularly in the field of electronics, OA and the like.

BACKGROUND OF THE INVENTION

Polycarbonate resins are thermoplastic resins having an excellent impactresistance, heat resistance and the like that are widely used in areassuch as electrical, electronic, OA, mechanical and automotiveapplications. In addition to the excellent performance exhibited bypolycarbonate resins, a material having excellent flame retardance isbeing sought to satisfy the safety demands encountered in theelectrical, electronic and OA fields. Therefore, many methods in whichan organic bromine compound or an inorganic compound represented byphosphorus type compounds or metal oxides is added to improve the flameretardance of polycarbonate resins have been proposed and used.

However, the generation of a gas containing a halogen upon combustion isa concern when a halogen type compound such as an organic brominecompound is formulated, and desired in the market is a flame retardingagent that does not contain chlorine, bromine and the like. Numerousresin compositions obtained by adding a phosphorus type flame retardingagent typified by phosphate esters have been proposed as halogen freematerials for flame retardant polycarbonate resins. To avoid theproblems of adhesion to metal molds and metal mold pollution whenmolding the composition, for example, condensation type phosphate estersderived from resorcin are used in particularly numerous cases.

Problems to be Solved by the Invention

However, polycarbonate resin compositions to which condensation typephosphate esters have been added do not necessarily provide asatisfactory balance of light and heat resistance, impact strength andfluidity. In addition, condensation type phosphate ester flame retardingagents had another problem associated with the lack of a synergisticflame retarding effect when a silicone compound of the present inventionwas used in combination.

Means to Solve the Problems

The inventors conducted a diligent study to solve the problems mentionedabove. As a result, the inventors made a surprising discovery that asynergistic flame retardant effect was realized when a composition wasobtained by adding a specific silicone compound and a phosphazenecompound having a specific structure to a polycarbonate resin.

In addition, not only was flame retardance provided, but also anexcellent balance was achieved among properties such as mechanicalstrength, molding properties, appearance and the like when a specificorganometallic salt and a fiber-forming type polymer containing fluorinewere added as well as when a specific titanium oxide and a polyorganohydrogen siloxane were also added in specific amounts as desired. Thepresent invention was completed based on these discoveries.

That is, the present invention is a flame retardant polycarbonate resincomposition comprising 100 parts by weight of a polycarbonate resin (A),0.01 to 3 parts by weight of a silicone compound (B) having a branchedchain structure and organic functional groups, wherein said organicfunctional groups comprise (i) aromatic groups or (ii) aromatic groupsand hydrocarbon groups (excluding aromatic groups), 0.5 to 20 parts byweight of a phosphazene compound (C), 0.01 to 2 parts by weight of anorganometallic salt (D) and 0.01 to 2 parts by weight of a fiber-formingtype fluorine-containing polymer (E). A specific titanium oxide (F) anda poly(organo hydrogen siloxane) (G) may also be added to thecomposition in specific amounts when desired. Such a flame retardantpolycarbonate resin composition exhibited extremely exceptionalperformance properties such as flame retardance, mechanical strength,molding properties, appearance and the like.

DISCLOSURE OF THE INVENTION

The present invention is illustrated in detail below.

The polycarbonate resin (A) used in the present invention is a polymerobtained using a phosgene method in which a variety of dihydroxydiarylcompounds is allowed to react with phosgene or in an ester exchangemethod in which a dihydroxydiaryl compound is allowed to react with acarbonate ester such as diphenyl carbonate. Polycarbonate resinsmanufactured using 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) arecited as typical examples.

In addition to bisphenol A, bis(hydroxyaryl)alkanes such asbis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl))octane,bis(4-hydroxyphenyl)phenylmethane,2,2-bis(4-hydroxyphenyl-3-methylphenyl)propane,1,1-(4-hydroxy-3-tertiary-butylphenyl)propane,2,2-bis(4-hydroxy-3-bromophenyl)propane,2,2-bis(4-hydroxy-3,5-dibromophenyl)propane and2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane;bis(hydroxyaryl)cycloalkanes such as1,1-bis(4-hydroxyphenyl)cyclopentane and1,1-bis(40hydroxyphenyl)cyclohexane; dihydroxydiaryl ethers such as4,4′-dihydroxydiphenyl ether and 4,4′-dihydroxy-3,3′-dimethyl diphenylether; dihydroxydiaryl sulfides such as 4,4′-dihydroxydiphenyl sulfide;dihydroxydiaryl sulfoxides such as 4,4′-dihydroxydiphenyl sulfoxide and4,4′-dihydroxy-3,3′-dimethyl diphenyl sulfoxide; and dihydroxydiarylsulfones such as 4,4′-dihydroxydiphenyl sulfone and4,4′-dihydroxy-3,3′-dimethyl diphenyl sulfone can be cited as thedihydroxydiaryl compound identified above,.

These compounds are used individually or as a mixture of at least two ofthem, but those containing no halogen substitution are preferred fromthe standpoint of preventing emission of a gas containing said halogenduring combustion that is a concern. In addition, piperazine,dipiperazyl hydroquinone, resorcinol and 4,4′-dihydroxydiphenyl and thelike may also be mixed and used.

Furthermore, the dihydroxyaryl compound identified above and a phenoliccompound having at least three hydroxyl groups may be mixed and used.Fluoroglucine, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptene,2,4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane,1,3,5-tri-(4-hydroxyphenyl)-benzol, 1,1,1-tri-(4-hydroxyphenyl-ethaneand 2,2-bis-[4,4-(4,4′-dihydroxydiphenyl)-cyclohexyl]-propane can becited as the phenol having at least three hydroxyl groups.

The viscosity average molecular weight of the polycarbonate resin (A) isordinarily 10,000 to 100,000 and is preferably 15,000 to 35,000. Whenmanufacturing such a polycarbonate resin, a molecular weight adjustingagent, a catalyst and the like can be used as necessary.

A silicone compound containing a branched main chain and containingorganic functional groups represented by the general formula (Chemicalformula 4) shown below

(in the formula R₁, R₂ and R₃ represent the organic functional groups onthe main chain and X represents terminal functional groups while n, mand 1 represent the number of moles of individual units) wherein saidorganic functional groups comprise aromatic groups or aromatic groupsand hydrocarbon groups (other than aromatic groups) may be used as thesilicone compound (B) in the present invention.

That is, it is preferred that the silicone compound (B) contains atleast 20 mole % of T units (RSiO_(1.5)) and/or Q units (SiO_(2.0)) basedon the total siloxane units (R₃₋₀SiO_(2-0.5)), wherein R represents anorganic functional group.

In addition, it is preferred that at least 20 mole % of the organicfunctional groups contained in the silicone compound (B) are aromaticgroups. Phenyl, biphenyl, naphthalene or their derivatives are preferredas the aromatic groups present, and phenyl groups are more preferred.The side chains that are not phenyl groups are preferably hydrocarbongroups containing no more than four carbon atoms, more preferably methylgroups. The terminal groups are preferably at least one selected fromthe group consisting of methyl group, phenyl group and hydroxyl group.

The average molecular weight (weight average) of the silicone compound(B) is preferably 3,000 to 500,000, and the range of 5,000 to 270,000 ismore preferred.

The amount of the silicone compound (B) added is 0.01 to 3 parts byweight per 100 parts by weight of the polycarbonate resin (A). Exceedingsaid range for the amount added is not desirable since the flameretarding effect is inadequate either way. More preferred is the rangeof 0.5 to 1.5 parts by weight.

As the phosphazene compound in the component (C) of the presentinvention, those compounds containing phosphorus and nitrogen in themolecule and previously well known can be used.

The phosphazene compound, for example, are:

-   -   (1) a cyclic phenoxyphosphazene represented by the general        formula (Chemical formula 1)

-   -   (wherein m represents an integer of 3 to 25, and Ph represents a        phenyl group),    -   (2) an open-chain phenoxyphosphazene represented by the general        formula (Chemical formula 2)

-   -   (wherein X¹ represents —N═P(OPh)₃ or —N═P(O)OPh, Y¹ represents        —P(OPh)₄ or —P(O)(OPh)₂, n represents an integer of 3 to 10,000        and Ph represents a phenyl group), and    -   (3) a crosslinked phenoxyphosphazene compound obtained by        crosslinking at least one compound selected from the group        consisting of said cyclic phenoxyphosphazenes and said        open-chain phenoxyphosphazenes with at least one crosslinking        group selected from the group consisting of o-phenylene group,        m-phenylene group, p-phenylene group and bis-phenylene group        represented by the general formula (Chemical formula 3)

-   -   (wherein Z represents —C(CH₃)₂—, —SO₂—, —S— or —O— and a        represents 0 or 1),    -   wherein (a) said crosslinking group exists between the two        oxygen atoms where phenyl groups of the phosphazene compounds        have been removed, (b) the proportion of phenyl groups is 50% to        99.9% based on the total number of total phenyl groups in said        phosphazene compound (Chemical formula 1) and/or said        phosphazene compound (Chemical formula 2) identified above,        and (c) no free hydroxyl group is present in the molecule.

The cyclic phenoxyphosphazene compound represented by the generalformula (Chemical formula 1) shown above and the open-chainphenoxyphosphazene compound represented by the general formula (Chemicalformula 2) shown above can be synthesized, for example, using a methoddescribed in H. R. Allcock, author, “Phosphorus-Nitrogen Compounds,”Academic Press (1972) or in J. E. Mark, H. R. Allcock, R. West, authors,“Inorganic Polymers”, Prentice-Hall International, Inc. (1992).

An example of the syntheses is described as follows. Ammonium chlorideis allowed to react with phosphorus pentachloride or is allowed to reactwith phosphorus trichloride and chlorine at about 120° C. to 130° C. inchlorobenzene or tetrachloroethane as the solvent. As a result, amixture of cyclic and open-chain dichlorophosphazene oligomers isobtained that is defined by the general formulae (Chemical formula 1)and (Chemical formula 2) wherein m and n are integer of 3 to 25 with theexception that the OPh groups in the formulae are instead chlorineatoms. The phosphazene compounds identified above can be manufactured bysubstituting this dichlorophosphazene oligomer mixture with phenol.

In addition, cyclic phenoxyphosphazene compounds such as hexaphenoxycyclotriphosphazene, octaphenoxy cyclotetraphosphazene, decaphenoxycyclopentaphosphazene and the like may be cited. Such compounds may beobtained through phenoxy substitution on a single cyclicdichlorophosphazene compound such as hexachlorocyclotriphosphazene,octachlorocyclotetraphosphazene, decachlorocyclopentaphosphazene and thelike and recovered using distillation or recrystallization from thecyclic and open-chain dichlorophosphazene oligomer mixture obtained inthe manner described above.

In addition, a open-chain phenoxyphosphazene compound obtained through aphenoxy substitution of a open-chain dichlorophosphazene represented bythe general formula (Chemical formula 2) wherein n represents an integerof 3 to 10,000 and obtained using a ring opening polymerization ofhexachlorocyclo triphosphazene by heating it to 220° C. to 250° C. canbe cited.

A dichlorophosphazene may be used in the form of a mixture of a cyclicdichlorophosphazene and a open-chain dichlorophosphazene or individuallyupon separation.

A crosslinked phenoxyphosphazene compound can be manufactured bysubstituting a portion of the phenyl groups in the cyclic and/oropen-chain phosphazene compound represented by the aforementionedgeneral formulae (Chemical formula 1) and/or (Chemical formula 2) withan aromatic dihydroxy compound containing one or at least two benzenerings and containing two hydroxyl groups, that is, by crosslinking usinga o-phenylene group, m-phenylene group, p-phenylene group and a(crosslinking) group represented by the aforementioned general formula(Chemical formula 3).

More specifically, a phenoxyphosphazene compound having high molecularweight due to a crosslinked construction and basically not containingterminal hydroxyl groups on one terminus of the dihydroxy compound canbe obtained by first allowing the aforementioned dichlorophosphazenecompound to react with a mixture of an alkali metal salt of a phenol andan alkali metal salt of a dihydroxy compound, synthesizing a partiallysubstituted material containing a portion of the chlorine in thechlorophosphazene compound as residual chlorine and subsequentlyallowing the product to react with an alkali metal salt of a phenol. Thereaction of the dichlorophosphazene compound with an alkali metal saltof a phenol and/or an aromatic dihydroxy compound is ordinarilyconducted at a temperature of room temperature to about 150° C. in asolvent composed of aromatic hydrocarbons such as toluene and the likeand halogenated aromatic hydrocarbons such as chlorobenzene and thelike.

The production method for a crosslinked phosphazene compound isexplained in further detail. In the first stage of the reaction, theamounts of an alkali metal salt of a phenol and an aromatic dihydroxycompound used per dichlorophosphazene oligomer should ordinarily beabout 0.05 to 0.9 equivalent (relative to the amount of chlorine in thedichlorophosphazene oligomer) or preferably about 0.1 to 0.8 equivalent(relative to the amount of chlorine) considering the total amounts ofboth alkali metal salts.

In the first stage of the reaction, the amount of the aromatic dihydroxycompound that can be used is small and the effect of the crosslinkedcompound is small when the amounts of an alkali metal salt of a phenoland an aromatic dihydroxy compound used per dichlorophosphazene oligomeris much lower than 0.05 equivalent. However, a crosslinkedphenoxyphosphazene compound containing essentially no terminal hydroxygroups on one end of the dihydroxy compound is difficult to obtain whenthe amount used grossly exceeds 0.9 equivalent.

The ratio (mole ratio of the alkali metal salt of an aromatic dihydroxycompound to the alkali metal salt of a phenol) of the two alkali metalsalts is not particularly restricted and can be appropriately selectedfrom a broad range, but it ordinarily should be about 1/2000 to ¼. Adesired crosslinked phenoxyphosphazene compound can be obtained withinthis range. When the usage ratio is much lower than 1/2000, the effectof the crosslinking compound can potentially decline, making theprevention of dripping of the polycarbonate resin more difficult.Conversely, when the usage ratio grossly exceeds ¼, the crosslinkingsometimes proceeds too extensively, and the crosslinkedphenoxyphosphazene compound obtained sometimes becomes insoluble andinfusible and its uniform dispersability in the resin sometimes candecline.

Next, in the second stage of the reaction, the amount of the phenolalkali metal salt used should ordinarily be about 1 to 1.5 equivalent(based upon the amount of chlorine in the dichlorophosphazene oligomer)and preferably about 1 to 1.2 equivalent (based upon the amount ofchlorine).

Resorcinol, hydroquinone, catechol, 4,4-isopropylidene diphenol(bisphenol A), 4,4′-sulfonyl diphenol (bisphenol S), 4,4′-thiodiphenol,4,4′-oxydiphenol and 4,4′-diphenols can be mentioned as the aromaticdihydroxy compound used to manufacture a crosslinked phosphazenecompound. In addition, sodium salts, potassium salts, lithium salts andthe like are preferred as alkali metal salts of the aromatic dihydroxycompound and/or phenol. One of the aromatic dihydroxy compounds may beused individually or at least two of them may be used in combination.

The phenyl group concentration in the crosslinked phenoxyphosphazenecompound is 50% to 99.9% based on the number of total phenyl groups inthe phosphazene compound (Chemical formula 1) and/or (Chemical formula2) identified above, and 70% to 90% is preferred.

The phosphazene compound used as component (C) in the present invention,that is, a cyclic phosphazene compound represented by the generalformula (Chemical formula 1), a open-chain phosphazene compoundrepresented by the general formula (Chemical formula 2) and acrosslinked phenoxyphosphazene compound obtained by replacing a portionof the phenyl groups in the cyclic and open-chain phosphazene compoundsrepresented by the aforementioned general formula (Chemical formula 1)and/or the general formula (Chemical formula 2) with o-phenyl groups,m-phenyl groups, p-phenyl groups and crosslinking groups and representedby the aforementioned general formula (Chemical formula 3) ismanufactured.

The open-chain and cyclic crosslinked phenoxyphosphazene compounds ofthe present invention do not contain halogen and do not generatehydrogen halide and the like gases and smoke when decomposed or burned.In addition, they do not cause a metal mold to corrode and a resin todeteriorate and discolor during a resin molding stage. In addition, thephenoxyphosphazene compound identified above does not depress themolding temperature of a resin, has low volatility and does not causeproblems such as blocking while kneading, bleeding (juicing), drippingduring combustion and the like.

In addition, a crosslinked phenoxyphosphazene compound of the presentinvention is a crosslinked phenoxyphosphazene compound that basicallydoes not contain a terminal hydroxy group on one end of a dihydroxycompound. Therefore, it does not depress molecular weight, mechanicalproperties such as impact resistance nor other properties such as heatresistance and molding properties inherent in the resin.

The amount of the phosphazene compound (C) added per 100 parts by weightof an aromatic polycarbonate resin is 0.5 to 20 parts by weight. Whenthe amount of a phosphazene compound added is less than 0.5 part byweight, the flame retardance is inadequate. When the amount exceeds 20parts by weight, the mechanical properties tend to be depressed readily.The amount of the phosphazene compound added per 100 parts by weight ofthe aromatic polycarbonate resin is preferably 1 to 20 parts by weight,but 4 to 10 parts by weight is more preferred.

The organometallic salt (D) includes a metal salt of an aromaticsulfonic acid and a metal salt of a perfluoroalkane sulfonic acid,preferably a potassium salt of4-methyl-N-(4-methylphenyl)sulfonylbenzene sulfonamide, a potassiumdiphenylsulfone-3-sulfonate, a potassiumdiphenylsulfone-3,3′-disulfonate, sodium para-toluene sulfonate, apotassium perfluorobutane sulfonate and the like.

The amount of the organometallic salt (D) added per 100 parts by weightof a polycarbonate resin (A) is 0.01 to 2 parts by weight. The option ofadding less than 0.01 part by weight is undesirable since the flameretardance declines. In addition, when the amount added exceeds 2 partsby weight the mechanical performance and flame retardance are sometimesnot obtained, and the problem of poorer surface appearance isencountered. A more preferable amount added is in the range of 0.2 to 1part by weight.

As the fiber-forming fluorine-containing polymer (E) used in the presentinvention, those forming a fibril construction in the polycarbonateresin (A) are preferred. For example, polytetrafluoroethylene,tetrafluoroethylene type copolymers (for example,tetrafluoroethylene/hexafluoropropylene copolymers and the like), thepartially fluorinated polymers shown in U.S. Pat. No. 4,379,910,polycarbonates manufactured from fluorinated diphenol and the like canbe mentioned. Polytetrafluoroethylenes having a molecular weight of atleast 1,000,000, a secondary particle size of at least 100 μm and anability to form fibrils are preferably used.

The amount of the fiber-forming fluorine-containing polymer (E) is 0.01to 2 parts by weight per 100 parts by weight. Drip prevention declineswhen the amount added is less than 0.01 part by weight. The option ofusing more than 2 parts by weight is not desirable since the surfaceappearance and mechanical performance (particularly impact resistance)decline. The range of 0.2 to 1 part by weight is more preferred.

Titanium oxide manufactured using either a chlorine method or a sulfuricacid method may be used as the titanium oxide (F) used in the presentinvention. As far as the crystal forms are concerned, either rutile typeor anatase type may be used. In addition, the particle size of titaniumoxide is preferably about 0.1 to 0.5 μm. A titanium oxide the surface ofwhich is treated by a phosphoric acidized polyene is preferred.

It is preferred that the extent of the surface treatment of saidtitanium oxide (F) is such an extent that the weight of containedphosphorus is about 0.04% to 0.1% by weight based on the weight of thetitanium oxide.

As the polyene, high molecular weight aliphatic acids containingmultiple unsaturated bonds within a molecular structure and a minimum often carbon atoms, preferably about eighteen carbon atoms, and a maximumof twenty-eight carbon atoms are used. As more specific examples of thepolyene, linolenic acid and linolic acid can be mentioned. In addition,mixtures of an aliphatic acid such as oleic acid that contains only oneunsaturated bond in a molecule and a saturated aliphatic acid such asstearic acid and the like may also be used, and, furthermore, phosphoricacidized material of various aliphatic acid derivatives may also bepresent. Alkyl aliphatic acid esters, aliphatic acid amides and the likemay be mentioned as more specific examples of such derivatives.

Many methods can be described for the phosphoric acidization of apolyene. The most commonly used means is a method using a Friedel-Kraftcatalyst, and the detailed procedures are disclosed in the well knownliterature listed below.

-   -   E. Jungermann and J. J. McBridge, J. Org. Chem. 26, 4182 (1961).    -   E. Jungermann and J. J. McBridge, R. Clutter and A. Masis, J.        Org. Chem. 27, 606 (1962).

Diphosphoric acid or diphosphoric acid esters of para-menthane can beidentified as other effective polyenes. General formula (Chemicalformula 5)

and general formula (Chemical formula 6)

(in the formulae (Chemical formula 5) and (Chemical formula 6), R₁, R₂,R₃ and R₄ individually represent hydrogen atoms or C1 to C10 alkylgroups.) can be cited as the structures.

The amount of titanium oxide (F) added is 5 to 25 parts by weight per100 parts by weight of a polycarbonate resin (A). When the amount addedis less than 5 parts by weight, the light blocking performance is poor.When the amount exceeds 25 parts by weight, the impact is undesirablesince the appearance and mechanical strength (particularly the impactstrength) decline. The more preferred range is 9 to 15 parts by weight.

Methyl hydrodiene polysiloxane, methyl hydrodiene polycyclohexane andthe like can be cited as the poly(organo hydrogen siloxane) (G). Thosecompounds selected from the structural units in the general formulaeshown below (Chemical formula 7) to (Chemical formula 9) areparticularly preferred. General formula (Chemical formula 7):(R)_(a)(H)_(b)Si_((4-a-b)/2)(wherein R is a monovalent hydrocarbon group containing no aliphaticunsaturation, a is 1.00 to 2.10, b is 0.1 to 1.0 and (a+b) is 2.00 to2.67.) General formula (Chemical formula 8):

(wherein A and B are individually selected from

and n is an integer of 1 to 500.)

General formula (Chemical formula 9):

(wherein A, B and n are defined as those shown in the general formula(Chemical formula 8)).

When other poly(organo hydrogen siloxanes) are used, the molecularweight of the polycarbonate resins sometimes declines, the degree ofyellowing sometimes rises when melting and kneading at hightemperatures, a large amount of gas is sometimes generated and silverstreaks and the like are sometimes created while molding.

The amount of the poly(organo hydrogen siloxane) (B) added is 0.05 to 2parts by weight. When the amount added is less than 0.05 part by weight,silver streaks are generated in molded products, flame retardancedeclines and impact strength declines. When the amount exceeds 2 partsby weight, silver streaks are generated in molded products and flameretardance worsens, making this an undesirable option.

The aforementioned titanium oxide (F) and poly(organo hydrogen siloxane)(G) can be added directly to a polycarbonate resin (A) as is. Inaddition, the surface of the titanium oxide (F) may also be treatedusing a poly(organo hydrogen siloxane) (G) before adding it to apolycarbonate resin (A).

As the aforementioned surface treatment method, either a wet or a drymethod may be used. In the wet method, titanium oxide (F) is added to amixed solution of a poly(organo hydrogen siloxane) (G) in a low boilingsolvent, the solution is agitated and the solvent is subsequentlyremoved. Furthermore, the product may be subsequently subjected to aheat treatment at a temperature of 120° C. to 200° C. In the dry method,a poly(organo hydrogen siloxane) (G) and titanium oxide (F) are mixedand agitated using a mixing device such as a super mixer, Henschelmixer, V type tumbler and the like. In this case, the product may alsobe subjected to a heat treatment at a temperature of 120° C. to 200° C.

Various additives such as a thermal stabilizing agent, an oxidationinhibitor, a fluorescent whitening agent, a filler, a mold releasingagent, a softening material, an electrostatic inhibitor and the like aswell as other polymers may also be added to an a aromatic polycarbonateresin composition in a range that does not interfere with the effect ofthe present invention.

Glass fibers, glass beads, glass flakes, carbon fibers, talc powder,clay powder, mica, aluminum borate whiskers, potassium titanatewhiskers, Wollastonite powder, silica powder, alumina powder and thelike, for example, may be cited as the filler.

Polyesters such as poly(ethylene terephthalate) and poly(butyleneterephthalate); styrene type polymers such as polystyrene, high impactpolystyrene and acrylonitrile-ethylene-propylene-diene type rubber(EPDM) .styrene copolymers; polypropylene and polymers ordinarily usedby forming an alloy with polycarbonate, for example, may be mentioned asother polymers.

DESCRIPTION OF THE EXAMPLES

The present invention is explained more specifically using the examplesbelow, but the present invention is not limited to these examples. Theterm “part” refers to “part by weight” unless otherwise noted.

The materials used in the experiments are described below.

-   1. Polycarbonate resin (henceforth abbreviated to “PC”).

Sumitomo Dow Caliber-200-20, molecular weight: 18,600.

-   2. Silicone compound (henceforth abbreviated to “SI”).

The silicone compounds were manufactured according to a commonlypracticed production method.

That is, a suitable amount of diorgano dichlorosilane, monoorganotrichlorosilane and tetrachlorosilane or their partially hydrolyzedcondensed material was dissolved in an organic solvent. Water was addedto allow hydrolysis to occur, and a partially condensed siliconecompound was formed. Furthermore, triorgano chlorosilane was added andallowed to react to complete the polymerization. The solvent wassubsequently distilled to separate it.

The structural characteristics of the silicone compound synthesizedusing the method described above are presented below.

-   -   The ratio of D/T/Q units in the main chain: 40/60/0 (mole ratio)    -   The phenyl group ratio in total organic functional groups*: 60        mole %    -   Terminal groups: Methyl group only.    -   Weight average molecular weight**: 15,000    -   The phenyl group was present, first of all, in the T units in a        silicone containing T units, and the remainder was present in D        units. When a phenyl group was attached to a D unit, the        presence of one was preferred but two were added when phenyl        groups were still available. With the exception of the terminal        groups, the organic functional groups other than phenyl groups        were all methyl groups.    -   The weight average molecular weight was reported using two        significant digits.

-   3. Phosphazane: The commercially available phosphazene listed below    was used.    -   Ohtsuka Kagaku. Phosphazane SPE-100 (melting point: 110° C.,        phosphorus content: 13%, henceforth abbreviated to “PZ”).

-   4. Phosphate ester {circle around (1)}: Asahi Denka Kogyo. Adekastub    FP500 (resorcinol dixylenyl phosphate: henceforth abbreviated to    “P1”).    -   Phosphate ester {circle around (2)}: Asahi Denka Kogyo.        Adekastub FP700 (bisphenol A diphenyl phosphate: henceforth        abbreviated to “P2”).    -   Phosphate ester {circle around (3)}: Asahi Denka Kogyo.        Adekastub PFR (resorcinol diphenyl phosphate: henceforth        abbreviated to “P3”).

-   5. Organometallic salt:    -   Sodium para-toluene sulfonate (henceforth abbreviated to        “PTSNa”).

-   6. Polytetrafluoroethylene:    -   Daikin Kogyo Co. Neofron FA500 (henceforth abbreviated to        “PTFE”).

-   7. Titanium oxide:

A titanium oxide the surface of which had been treated using aphosphoric acidized polyene material (linolenic acid was used as thepolyene and the acid was modified using phosphoric acid). (Thephosphorus concentration in the titanium oxide was 0.06%.) Alumina wasused as the inorganic surface treatment agent of said titanium oxide.(Henceforth abbreviated to “TiO₂”.)

-   8. Poly(organo hydrogen siloxane):    -   Shin-Etsu Kagaku Kogyo Co. KF99 (viscosity: 20 cSt, 25° C.).        (Henceforth abbreviated to “MHSO”.)

In a formulation method the various starting materials described abovewere added in a single addition to a tumbler in the formulation ratiosshown in Tables 1 to 3 and were dry blended. A biaxial extruder (KobeSeiko Co., KTX37) was used to melt and knead the mixture at a fusiontemperature of 280° C. to obtain pellets of a flame retardantpolycarbonate resin composition.

Test pieces for the evaluation of ASTM specified mechanical propertiesand test pieces (0.8 mm thick) for the evaluation of flame retardanceaccording to UL94 were prepared from the pellets obtained at a melttemperature of 300° C. using a J100E-C5 injection molding devicemanufactured by Nippon Seiko Co.

The evaluation methods are described below.

1. Impact Strength:

A notched Izod impact strength was measured according to the provisionsof ASTM D256 at 23° C. using ⅛ inch thick pieces. A numerical value ofat least 35 kg·cm/cm was needed to be rated as “pass”.

2. Flame Retardance:

The flame retardance was evaluated according to the provisions of theUL94·V vertical combustion testing method described below.

A test piece was left standing for 48 hours in a constant temperaturechamber maintained at 23° C. and 50% humidity, and the flame retardancewas evaluated according to the provisions of the UL94 test (a combustiontest for a plastic material used in instrument parts) instituted byUnderwriters Laboratories. UL94V refers to a test conducted bycontacting a vertically oriented test piece of a designated size with aburner flame for ten seconds. The duration of time during which residualflame remained, the amount of dripping and the flame retardance wereevaluated. The ratings are as follows:

V-0 V-1 V-2 Afterflame of each specimen ≦10 sec.  ≦30 sec.  ≦30 sec.Totalafterflame of five specimen ≦50 sec. ≦250 sec. ≦250 sec. Ignitionof cotton by dropping no no yes

The term “afterflame” as used herein means the period of time in which atest specimen continues burning after the source of ignition has beenmoved away. “The ignition of cotton by dripping” means whether or not apiece of cotton placed about 300 mm below the lower end of a specimencatches fire from a drip of melt from the specimen. The evaluationgraded a 1.0 mm thick test piece a “pass” when it qualified for aranking of V-0.

3. Deflection Temperature Under Load:

A test piece 6.4 mm thick was evaluated using an HDT tester manufacturedby Toyo Seiki at a fiber stress of 18.6 kg/cm². A temperature of atleast 105° C. received a “pass” grading.

4. Light Reflectivity:

A three-stage test piece plate (thicknesses 3 mm, 2 mm and 1 mm) 90 mmlong and 40 mm wide was prepared, and a spectrophotometer (ModelCMS-35SP manufactured by Murakami Shikisai Gijutsu Kenkyusho) was usedto measure the Y value for the 1 mm thick section at a wavelength of 400nm to 800 nm. Next, a Sunshine Weathermeter (black panel temperature:83° C./no rain) manufactured by Suga Shikenki was used, and said testpiece was exposed to light irradiation for 250 hours. The Y value wasmeasured in the same manner as the Y value was measured for unexposedtest pieces. A Y value of at least 94 was considered passing.

5. Degree of Yellowing (Henceforth Abbreviated to “ΔYI”).

A spectrophotometer (Model CMS-35SP manufactured by Murakami ShikisaiGijutsu Kenkyusho) was used according to the provisions of ASTM D1925,and test pieces having length×width×thickness=60×60×3.2 mm were used forthe measurements. ΔYI refers to the value obtained by subtracting the YIvalue measured using the Sunshine Weathermeter prior to exposure (theinitial value) from the YI value after exposure. A ΔYI of no greaterthan 17 was considered passing.

6. Silver Streaks:

Three-stage test piece plates (3, 2 and 1 mm thickness) 90 mm long and40 mm wide were prepared using a Model J100E-C5 injection moldingmachine manufactured by Nippon Steel at a melting temperature of 320°C., and the silver streaks generated on the surface were visuallyexamined.

The amounts of individual components formulated and the test results aresummarized in Tables 1 to 3.

TABLE 1 Compositions and Test Results Working Examples 1 2 3 PC, parts100 100 100 SI, parts 1.5 0.7 1.5 PZ, parts 5 5 10 PTSNa, parts 0.2 0.20.2 PTFE, parts 0.4 0.4 0.4 Flame retardance V-0 V-0 V-0 UL94 NotchedIzod impact 70 65 40 strength kg · cm/cm Deflection 117 117 105temperature under load, ° C.

TABLE 2 Compositions and Test Results Comparative Examples 1 2 3 4 5 6 7PC, parts 100 100 100 100 100 100 100 SI, parts 1.5 1.5 1.5 1.5 1.50.005 4 PZ, parts — — — 0.3 21 5 5 P1, parts 5 — — — — — — P2, parts — 5— — — — — P3, parts — — 5 — — — — PTSNa, 0.2 0.2 0.2 0.2 0.2 0.2 0.2parts PTFE, 0.4 0.4 0.4 0.4 0.4 0.4 0.4 parts Flame NR NR NR NR V-0 NRNR retardance UL94 Notched 13 13 13 80 8 15 85 Izod impact strength kg ·cm/cm Deflection 112 111 110 130 75 117 117 temperature under load, ° C.

TABLE 3 Compositions and Test Results Example Comparative Example 4 8 910 11 12 PC, parts 100 100 100 100 100 100 SI, parts 1.5 1.5 1.5 1.5 1.51.5 PZ1 5 — 5 5 5 5 P1, parts — 5 — — — — P2, parts — — — — — — P3,parts — — — — — — PTSNa, parts 0.2 0.2 0.2 0.2 0.2 0.2 PTFE, parts 0.40.4 0.4 0.4 0.4 0.4 TiO₂, parts 11 11 3 30 11 11 POHS, parts 0.5 0.5 0.50.5 3 0.03 Flame retardance V-0 NR V-0 NR NR NR UL94 Notched Izod impact60 10 70 10 65 25 strength kg · cm/cm Deflection temperature 117 112 117117 115 117 under load, ° C. Silver streak ◯ ◯ ◯ ◯ X X Degree ofyellowing, 15 45 17 13 15 15 ΔYI Light Before 96 96 87 97 96 93reflectivity irradiation After 95 88 85 96 94 91 irradiation Note: NR isan abbreviation for “no rating”.

As shown by the data for Working Examples 1 to 4, all specifications forflame retardance, optical properties, notched Izod impact strength,deflection temperature under load, degree of yellowing and lightreflectivity were satisfied when the essential components of the presentinvention were used and the formulation rates of each component werewithin the range specified.

In contrast, each sample encountered problems when components other thanthe essential components of the present invention were used or theamount of essential components used did not satisfy the specified range.

Phosphazane Compound:

When the amount added was less than the range specified, as was the casein Comparative Example 4, flame retardance was not realized. Incontrast, when the amount exceeded the range specified, as it did inComparative Example 5, properties such as impact strength and deflectiontemperature under load declined extensively.

Silicone Compound:

When the amount added was less than the range specified, as was the casein Comparative Example 6, the desired flame retardance and impactstrength were not realized. Similarly, the flame retardancespecifications were not satisfied when the specified range was exceededas it was in Comparative Example 7.

Phosphate Ester:

In Comparative Examples 1, 2 and 3, a silicone compound and a phosphateester of the present invention were used in combination. However, nosynergistic effect of the two compounds was observed at all, and variousmeasures of performance even declined. [The table stops at comparativeexample 7]

In Comparative Example 8, the impact strength declined extensively. Inaddition, the degree of yellowing (ΔYI) and the reflectivity (ΔY)declined so extensively that the material did not satisfy thespecifications.

Titanium Oxide:

The amount of titanium oxide added in Comparative Example 9 was muchless than the lower limit of the specified range, and the lightreflectivity did not satisfy the specifications. In contrast, inComparative Example 10 when the amount of titanium oxide added exceededthe upper limit of the specified range, flame retardance and impactstrength did not satisfy the specifications.

Organo Hydrogen Siloxane:

In Comparative Example 11, the amount of organo hydrogen siloxane addedexceeded the upper limit of the specified range. In this case, flameretardance declined and the amount of hydrogen gas generated wasextremely large causing a pronounced silver streak generation. Inaddition, the amount of organo hydrogen siloxane added in ComparativeExample 12 was lower than the specified range. In this case, flameretardance and impact resistance declined and silver streaks were alsogenerated.

Advantages of the Invention

Since the flame retardant polycarbonate resin composition of the presentinvention does not contain a halogen type flame retarding agentcomprising chlorine compounds, bromine compounds and the like, no gasderived from a halogen type flame retarding agent are generated whenburned. Furthermore, the composition is not only provided with a highdegree of flame retardance and light reflectivity but also has excellentimpact resistance, heat resistance, light resistance and the like andcan preferably be used as a material for various internal and externaluses associated with electrical, electronic and OA applications.

1. A flame retardant polycarbonate resin composition comprising 100parts by weight of a polycarbonate resin (A), 0.01 to 3 parts by weightof a silicone compound (B) having a branched chain structure and organicfunctional groups, wherein said organic functional groups comprise (i)aromatic groups or (ii) both aromatic groups and non-aromatichydrocarbon groups, 0.5 to 20 parts by weight of a phosphazene compound(C), 0.01 to 2 parts by weight of an organometallic salt (D), 0.01 to 2parts by weight of a fiber-forming type fluorine-containing polymer (E),5 to 25 parts by weight of titanium oxide (F) per 100 parts by weight ofa polycarbonate resin (A) and 0.05 to 2 parts by weight of a poly(organohydrogen siloxane) (G), per 100 parts by weight of a polycarbonate resin(A).
 2. The flame retardant polycarbonate resin composition of claim 1wherein said silicone compound (B) contains at least 20 mole % of unitshaving the formula RSiO_(0.5) (T units) and/or units having the formulaSiO_(2.0) (Q units) based on the total siloxane units (R₃₋₀SiO_(2-0.5)),wherein R represents an organic functional group.
 3. The flame retardantpolycarbonate resin composition of claim 1 wherein at least 20 mole % ofthe organic functional groups contained in the silicone compound (B) arearomatic groups.
 4. The flame retardant polycarbonate resin compositionof claim 1 wherein in the organic functional groups contained in thecompound (B) the aromatic groups are phenyl groups, the side chains thatare not phenyl groups are methyl groups and the terminal groups are atleast one selected from the group consisting of methyl group, phenylgroup and hydroxyl group.
 5. The flame retardant polycarbonate resincomposition of claim 1 wherein said phosphazene compound is at least oneselected from the group consisting of: (1) a cyclic phenoxyphosphazenerepresented by the general formula (Chemical formula 1)

(wherein m represents an integer of 3 to 25, and Ph represents a phenylgroup), (2) an open-chain phenoxyphosphazene represented by the generalformula (Chemical formula 2)

(wherein X¹represents —N═P(OPh)₃ or —N═P(O)OPh, Y¹represents —P(OPh)₄ or—P(O)(OPh)₂, n represents an integer of 3 to 10,000 and Ph represents aphenyl group), and (3) a crosslinked phenoxyphosphazene compoundobtained by crosslinking at least one compound selected from the groupconsisting of said cyclic phenoxyphosphazenes and said open-chainphenoxyphosphazenes with at least one crosslinking group selected fromthe group consisting of o-phenylene group, m-phenylene group,p-phenylene group and bis phenylene group represented by the generalformula (Chemical formula 3)

(wherein Z represents —C(CH₃)₂—, —SO₂—, —S— or —O— and a represents 0 or1), wherein (a) said crosslinking group exists between two oxygen atomswhere phenyl groups of the phosphazene compounds have been removed, (b)the proportion of phenyl groups is 5000 to 99.900 based on the totalnumber of total phenyl groups in said phosphazene compound (Chemicalformula 1) andlor said phosphazene compound (Chemical formula 2)identified above, and (c) no free hydroxyl group is present in themolecule.
 6. The flame retardant polycarbonate resin composition ofclaim 1 wherein said organometallic salt (D) is a metal salt of anaromatic sulfonic acid or a metal salt of a perfluoroalkane sulfonicacid.
 7. The flame retardant polycarbonate resin composition of claim 1wherein said fiber-forming fluorine-containing polymer (E) ispolytetrafluoroethylene.
 8. The flame retardant polycarbonate resincomposition of claim 1 wherein said titanium oxide (F) is a titaniumoxide the surface of which is treated by a phosphoric acidized polyene.9. The flame retardant polycarbonate resin composition of claim 8wherein the extent of the surface treatment of said titanium oxide (F)is that the weight of contained phosphorus is about 0.04% to 0.1% byweight based on the weight of the titanium oxide.
 10. The flameretardant polycarbonate resin composition of claim 2 wherein at least 20mole % of the organic functional groups contained in the siliconecompound (B) are aromatic groups.
 11. The flame retardant polycarbonateresin composition of claim 10 wherein, in the organic functional groupscontained in the compound (B), the aromatic groups are phenyl groups,the side chains that are not phenyl groups are methyl groups, and theterminal groups are at least one selected from the group consisting ofmethyl group, phenyl group and hydroxyl group.
 12. The flame retardantpolycarbonate resin composition of claim 11 wherein said phosphazenecompound is at least one selected from the group consisting of: (1) acyclic phenoxyphosphazene represented by the general formula (Chemicalformula 1)

(wherein m represents an integer of 3 to 25, and Ph represents a phenylgroup), (2) an open-chain phenoxyphosphazene represented by the generalformula (Chemical formula 2)

(wherein X¹represents N═P(OPh)₃ or —N═P(O)OPh, Y¹represents —P(OPh)₄ or—P(O)(OPh)₂, n represents an integer of 3 to 10,000 and Ph represents aphenyl group), and (3) a crosslinked phenoxyphosphazene compoundobtained by crosslinking at least one compound selected from the groupconsisting of said cyclic phenoxyphosphazenes and said open-chainphenoxyphosphazenes with at least one crosslinking group selected fromthe group consisting of o-phenylene group, m-phenylene group,p-phenylene group and bis phenylene group represented by the generalformula (Chemical formula 3)

(wherein Z represents C(CH₃)₂—, —SO₂—, —S— or —O— and a represents 0 or1), wherein (a) said crosslinking group exists between the oxygen atomswhere phenyl groups of the phosphazene compounds have been removed, (b)the proportion of phenyl groups is 50% to 99.9% based on the totalnumber of total phenyl groups in said phosphazene compound (Chemicalformula 1) andlor said phosphazene compound (Chemical formula 2)identified above, and (c) no free hydroxyl group is present in themolecule.
 13. The flame retardant polycarbonate resin composition ofclaim 12 wherein said organometallic salt (D) is a metal salt of anaromatic sulfonic acid or a metal salt of a perfluoroalkane sulfonicacid.
 14. The flame retardant polycarbonate resin composition of claim13 wherein said fiber-forming fluorine-containing polymer (E) ispolytetrafluoroethylene.
 15. The flame retardant polycarbonate resincomposition of claim 14 wherein said titanium oxide (F) is a titaniumoxide the surface of which is treated by a phosphoric acidized polyene.16. The flame retardant polycarbonate resin composition of claim 15wherein the extent of the surface treatment of said titanium oxide (F)is that the weight of contained phosphorus is about 0.04% to 0.1% byweight based on the weight of the titanium oxide.